Where can I get free packing boxes?

A friend just posted a question on facebook: "Where can I get free packing boxes?". I can help with this because I work at a company which throws out hundreds of useful boxes every day.

The trick is to find a food distribution company near you, they often use boxes that are opened during delivery and come back empty.

The boxes can't be reused because they aren't "new". I work for a coffee company and we throw out (recycle) hundreds of boxes a day which can't be reused simply because they were taped shut and once that seal is cut open they need to use new boxes.

Especially if you live near an industrial area, you might find free packing boxes if you just drive there and ask some of the companies with large delivery truck loading ports.